Dubbo在项目中的应用
关于dubbo的使用,我们举个简单例子:
存在2个系统,A系统和B系统,A系统调用B系统的接口获取数据,用于查询用户列表。
在上一篇博文介绍了dubbo的创建,zookeeper的创建完成后,我们可以来使用dubbo和zookeeper了?
再回顾下dubbo的架构:
所以通过此图,我们看到就是服务的提供者将服务注册到注册中心,服务的消费者从注册中心获取服务,monitor监控服务的调用。
所谓框架无非就是配置文件+java代码,所以dubbo也同理:
(1)首先看下B服务的提供者的配置文件和代码:
搭建b系统:
建立一个maven的war工程,导入依赖
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<project xmlns= "http://maven.apache.org/POM/4.0.0" xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation= "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" >
<modelVersion> 4.0 . 0 </modelVersion>
<groupId>cn.itcast.dubbo</groupId>
<artifactId>dubbo-b</artifactId>
<version> 1.0 . 0 -SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<!-- dubbo采用spring配置方式,所以需要导入spring容器依赖 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version> 4.1 . 3 .RELEASE</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version> 1.6 . 4 </version>
</dependency><br data-filtered= "filtered" > //zookeeper的依赖需要导入,因为需要使用zkclient
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<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.3.3</version>
</dependency>
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>zkclient</artifactId>
<version>0.1</version>
</dependency>
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<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version> 2.5 . 3 </version>
<exclusions>
<exclusion>
<!-- 排除传递spring依赖 -->
<artifactId>spring</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version> 2.2 </version>
<configuration>
<port> 8081 </port>
<path>/</path>
</configuration>
</plugin>
</plugins>
</build>
</project> |
第二步:创建user对象:注意这里一定要实现序列化,并获取序列化的序号:
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//关于这个的获取,直接点击小黄色图标,既可以自动生成 |
1 |
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package cn.itcast.dubbo.pojo;
// 使用dubbo要求传输的对象必须实现序列化接口 public class User implements java.io.Serializable {
private static final long serialVersionUID = -2668999087589887337L;<br data-filtered= "filtered" > //关于这个的获取,直接点击小黄色图标,既可以自动生成
private Long id;
private String username;
private String password;
private Integer age;
public Long getId() {
return id;
}
public void setId(Long id) {
this .id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this .username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this .password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this .age = age;
}
} |
创建服务接口和服务接口的实现类:
接口为了暴露服务的:
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5.3 . 5 . 创建UserService(接口)提供查询服务
package cn.itcast.dubbo.service;
import java.util.List;
import cn.itcast.dubbo.pojo.User;
public interface UserService {
/**
* 查询所有的用户数据
*
* @return
*/
public List<User> queryAll();
} 5.3 . 6 . 创建UserServiceImpl实现类
package cn.itcast.dubbo.service.impl;
import java.util.ArrayList;
import java.util.List;
import cn.itcast.dubbo.pojo.User;
import cn.itcast.dubbo.service.UserService;
public class UserServiceImpl implements UserService {
/**
* 实现查询,这里做模拟实现,不做具体的数据库查询
*/
public List<User> queryAll() {
List<User> list = new ArrayList<User>();
for ( int i = 0 ; i < 10 ; i++) {
User user = new User();
user.setAge( 10 + i);
user.setId(Long.valueOf(i + 1 ));
user.setPassword( "123456" );
user.setUsername( "username_" + i);
list.add(user);
}
return list;
}
} |
下面就是dubbo的服务提供者的配置文件了:
实际项目中,相当于服务的提供者的第一步:编写配置文件
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<beans xmlns= "http://www.springframework.org/schema/beans"
xmlns:context= "http://www.springframework.org/schema/context" xmlns:p= "http://www.springframework.org/schema/p"
xmlns:aop= "http://www.springframework.org/schema/aop" xmlns:tx= "http://www.springframework.org/schema/tx"
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo= "http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="http: //www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http: //www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http: //www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http: //code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<!-- 提供方应用信息,用于计算依赖关系 -->
<dubbo:application name= "dubbo-b-server" />
<!-- 这里使用的注册中心是zookeeper -->
<dubbo:registry address= "zookeeper://127.0.0.1:2181" client= "zkclient" />
<!-- 用dubbo协议在 20880 端口暴露服务 -->
<dubbo:protocol name= "dubbo" port= "20880" />
<!-- 将该接口暴露到dubbo中 -->
<dubbo:service interface = "cn.itcast.dubbo.service.UserService" ref= "userServiceImpl" />
<!-- 将具体的实现类加入到Spring容器中 -->
<bean id= "userServiceImpl" class = "cn.itcast.dubbo.service.impl.UserServiceImpl" /><br data-filtered= "filtered" > //监控的配置<br data-filtered="filtered"> <dubbo:monitor protocol="registry"></dubbo:monitor>
</beans> |
这里spring与dubbo进行了无缝整合,所以这里进行了spring与dubbo的整合:
第二步:读取配置文件
我们需要在web.xml中将配置文件引入:
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<?xml version= "1.0" encoding= "UTF-8" ?>
<web-app xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xmlns= "http://java.sun.com/xml/ns/javaee" xsi:schemaLocation= "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id= "WebApp_ID" version= "2.5" >
<display-name>dubbo-b</display-name>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:dubbo/dubbo-*.xml</param-value>
</context-param>
<!--Spring的ApplicationContext 载入 -->
<listener>
<listener- class >org.springframework.web.context.ContextLoaderListener</listener- class >
</listener>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app> |
第三步:配置服务消费者:
这里我们建立a的系统:
建立一个maven的jar工程:
导入依赖:
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<project xmlns= "http://maven.apache.org/POM/4.0.0" xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation= "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" >
<modelVersion> 4.0 . 0 </modelVersion>
<groupId>cn.itcast.dubbo</groupId>
<artifactId>dubbo-a</artifactId>
<version> 0.0 . 1 -SNAPSHOT</version>
<dependencies>
<!-- dubbo采用spring配置方式,所以需要导入spring容器依赖 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version> 4.1 . 3 .RELEASE</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version> 1.6 . 4 </version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version> 2.5 . 3 </version>
<exclusions>
<exclusion>
<!-- 排除传递spring依赖 -->
<artifactId>spring</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version> 3.3 . 3 </version>
</dependency>
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>zkclient</artifactId>
<version> 0.1 </version>
</dependency>
</dependencies>
</project> |
从b系统拷贝:
1.1.1. 从b系统中拷贝User对象、UserService接口道a系统
服务的消费者配置:
dubbo-consumer.xml
:
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dubbo-consumer.xml: <beans xmlns= "http://www.springframework.org/schema/beans"
xmlns:context= "http://www.springframework.org/schema/context" xmlns:p= "http://www.springframework.org/schema/p"
xmlns:aop= "http://www.springframework.org/schema/aop" xmlns:tx= "http://www.springframework.org/schema/tx"
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo= "http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="http: //www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http: //www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http: //www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http: //code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<!-- 提供方应用信息,用于计算依赖关系 -->
<dubbo:application name= "dubbo-a-consumer" />
<!-- 这里使用的注册中心是zookeeper -->
<dubbo:registry address= "zookeeper://127.0.0.1:2181" client= "zkclient" />
<!-- 从注册中心中查找服务 -->
<dubbo:reference id= "userService" interface = "cn.itcast.dubbo.service.UserService" />
</beans> |
编写测试:代码
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package cn.itcast.dubbo.service;
import static org.junit.Assert.*;
import java.util.List;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.itcast.dubbo.pojo.User;
public class UserServiceTest {
private UserService userService; //从这里我们可以看出,使用了dubbo后感觉调用服务是在自己的工程一样,但是其实我们是调用的b系统,因为b将服务接口暴露出来了,我们通过访问注册中心的服务接口来获取服务的实现。
@Before
public void setUp() throws Exception {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
"classpath:dubbo/*.xml" );
this .userService = applicationContext.getBean(UserService. class );
}
@Test
public void testQueryAll() {
List<User> users = this .userService.queryAll();
for (User user : users) {
System.out.println(user);
}
}
} |
这个是dubbo的简单入门程序,具体在项目中也是同样的道理。
不过上面代码有重复,我们可以家里一个公共的maven来存放pojo和服务接口,然后ab工程添加依赖即可。
在我们的项目中,一般步骤如下;
(1)导入dubbo、zookeeper依赖
(2)在服务提供者端,编写服务接口,服务接口的实现类,编写配置文件
(3)修改web.xml读取配置文件
(4)在服务消费者,即客户端,调用服务接口,调用服务实现类,编写配置文件
这样系统间就可以互相通信,从而感觉像在本地使用一样。
使用dubbo不像httpclient一样json的转换,因为dubbo都自动进行了。